1. Field of the Invention
The present invention relates to an ion implantation apparatus, and more particularly, to an ion implantation apparatus for use in manufacturing a semiconductor device, which has a software program including an option for allowing selection of a manipulator, thereby enabling a time for beam tuning to be minimized.
2. Discussion of the Related Art
Generally, ion implantation for implanting impurities into a silicon wafer has characteristics which can overcome limitations of a thermal diffusion method, such as a lower frequency of impurity diffusion towards a side surface (in comparison to the thermal diffusion method) and/or lower temperature processing (e.g., a lower thermal budget), leading to more accurate formation of a doped area without damaging a photoresist, and the like. Thus, ion implantation has been widely used in manufacturing integrated semiconductor devices.
An ion implantation apparatus is an apparatus for implanting impurity ions by selecting and accelerating the impurity ions, generally in a predetermined amount. Ion implantation apparatuses may be classified into medium-current ion implantation apparatuses, high-current ion implantation apparatuses, and high-energy ion implantation apparatuses, according to process conditions. The ion implantation apparatus generally comprises an ion generator (hereinafter referred to as a “manipulator”), a beam line, and an end station as main components.
The manipulator may comprise a source head for ionizing a gas by forcing a source gas to collide with thermal electrons emitted from a filament, an extraction electrode for extracting ions by applying an electromagnetic field to the respective ions, and a suppressor for suppressing secondary electrons from being generated when generating ion beams and extracting the ions by use of the electromagnetic field.
The source head is equipped with an arc chamber in which the ion beam is generated and a disc having a front slit positioned after the arc chamber in the path of ion beam, so that when the ion beam exits the arc chamber by virtue of the electromagnetic field, it passes through the front slit of the disc.
A conventional ion implantation apparatus for use in manufacturing a semiconductor device will be described with reference to the accompanying drawings.
FIG. 1 is a diagram illustrating the structure of a manipulator of the conventional ion implantation apparatus.
The conventional ion implantation apparatus of FIG. 1 generally comprises a manipulator for extracting and focusing a source and a beam, an analyzer magnet for distinguishing desired ions among the plural ions extracted from the manipulator, and an end station on which a wafer to be ion implanted is located and is subjected to ion implantation.
In the ion implantation apparatus constructed as described above, operation of the manipulator for extracting and focusing the beam is shown in FIG. 1.
While moving in X, Y, and Z directions, the manipulator optimizes the beam generating conditions, and transfers the beam conditions to the analyzer magnet in the next stage.
Movement of an electrode in the three directions as mentioned above is driven by an encoder motor (not shown), and, when the beam set up is completed, encoder values of the respective directions are stored in a recipe.
Accordingly, when performing ion implantation with the encoder values of the associated recipe, the encoder values of the associated recipe are taken from a control block controlling the ion implantation apparatus, thereby reducing a time for setting the respective directions of the manipulator.
Here, the time for setting the respective directions generally takes about 2˜3 minutes for ion implantation using a recipe having different encoder values.
However, since there may be an error (e.g., in alignment of) the respective axes between the manipulators in such a conventional ion implantation apparatus, there may be problems as follows, particularly when replacing a manipulator assembly with a new one during a prevention maintenance cycle (also referred to as a “PM cycle”).
For example, when using two manipulator assemblies A and B, in which the center of X is set to 500 for the manipulator assembly A and to 550 for the manipulator assembly B, problems may arise as follows when replacing the one manipulator assembly with another at the PM cycle.
When setting up or establishing a beam after replacing a first manipulator assembly A with a second manipulator assembly B, since a computer adapted to control the apparatus cannot recognize the replaced manipulator assembly, the manipulator assembly B is set up or initiated with the values of the manipulator assembly A, while a beam current is controlled using different conditions such as an arc current and a source magnet, causing consumption of time for beam tuning.
Additionally, during a process of setting up the manipulator B using the values of the manipulator assembly A, the manipulator assembly B may be off-center. However, even in this case, since the previous recipe of the manipulator assembly A is still used for the manipulator assembly B, the computer may make an error in determining that the manipulator assembly B is located at the center of the chamber.
Such increases in set up time for beam tuning and a location determination error cause reductions in productivity. This reduction of productivity is serious in a semiconductor wafer foundry that may use a number of recipes for the same ion implantation equipment and/or process.